Getting "NullPointerException" after upgrading Minecraft launcher [duplicate]

Solution 1:

I found a solution myself:

1. rename the ~/.minecraft directory directory so Minecraft can't find it.
2. start Minecraft again and start a fresh game. This will generate a new ~/.minecraft directory.
3. Exit Minecraft and copy the saved games from the renamed ~/.minecraft/saves directory into the new one.
4. Start Minecraft again and confirm it's working now.

This did the trick for me!

As per the bug report linked below, the fix might be even simpler than my steps above:

1. edit ~/.minecraft/options.txt and find the line starting with lang=. Note the parameter value is all lowercase.
2. Change the last two characters from lowercase to uppercase. E.g., change from en_en to en_EN.
3. Save and try Minecraft again.